It's essential to remain always in the character's point of view.
No matter if you're writing in first person point of view, third person limited point of view, or third person omniscient point of view, you need always to to describe things from the character's point of view rather than the author's point of view. The reason for this is that the author has to be invisible in the story, and so the only points of view left are the characters', after all.
Slipping out of the character's point of view, and into the author's point of view, jars the reader, and breaks him out of the reading trance we - as writers - are always aiming to keep him in.
As you'll read elsewhere on this website, the deal is that the reader agrees to pretend this stuff is true, and we agree to make it as easy as possible for him to pretend that this stuff is true!
When I do critiques, one of the major problems I see is what I could call POV-slippage. So it's worth while going into this in some detail and showing you some hints and tips to avoid it.
Have a read of this:
Jane answered the door to find her new next-door neighbour standing there. He was six foot one, with soft brown eyes under thick black brows, sharp cheekbones and a friendly smile on a wide mouth.
Now, if I were to read that, immediately I'd be thinking (subconsciously at least, even if I didn't articulate it to myself): Hang on a second! How does Jane know his exact height? Does she have a measuring tape there? Is her door post calibrated???
The truth of course is that Jane cannot know exactly how tall the man is. The author knows for sure - after all, the author has created this man, he would know everything about him. But as I said above, the author should be invisible. It's only Jane's experience that the reader can share.
But this is easily solved with just a word or two. Here's the better version, with literally just three words added (shown in bold):
Jane answered the door to find her new next-door neighbour standing there. He was about six foot one, she judged, with soft brown eyes under thick black brows, sharp cheekbones and a friendly smile on a wide mouth.
Do you see the difference? Jane is guessing his height, and that's fine. The reader will take this on board that she's right, and his height is six foot one - but the information will be brought across through the character's point of view (Jane's, in this case).
In the following example, we're in Martin's point of view (as would have been very clear in the preceding text if this was a real story).
Martin left his muddy boots at the back door and went into the kitchen. Kate had heard him coming and had put on the kettle.
Okay, same problem: How does Martin know for a fact that Kate had heard him? He doesn't. Only the author knows that.
It would be much better to write:
Martin left his muddy boots at the back door and went into the kitchen. Kate must have heard him coming as she was putting on the kettle.
Again, it's a very subtle tweak but an important one. It is now Martin deducing that Kate was putting on the kettle, rather than the author stating it. Again, Martin doesn't know for a fact, but if that assumption is good enough for him, it's good enough for the reader.
And yes, we didn't write, Martin thought Kate must have heard him ... But that's okay; it's understood.
In every case it'll only take tiny tweaking to make sure that it's the character's point of view which is being shared, not the author's. But be very aware of it, and do make checking this part of your editing process.